I‘ve had almost the same experience. First I was super impressed how easy it is to get data into BigQuery and retrieve it using their IDE.

But really soon I noticed the slow startup … simple queries took too long (1.2 sec vs milliseconds in a traditional database)

Then I learned a lot about BigQuery views. That helped a little.

At some point I simply wanted to export data. New Google tools needed to be learned: Cloud Storage, Data Flow.

After 18 months of using BigQuery on roughly 850 million rows, I switched back to a traditional database.